Sciencemadness Discussion Board - Poly-Azido-Prene from Neoprene

Poly-Azido-Prene from Neoprene

DubaiAmateurRocketry - 30-5-2018 at 01:27

So similar to the synthesis of:

Glycidyl chloride polymer > GAP

and PVC to PVazide.

What about Polychloroprene to polyazidoprene?

Here is a possible route? any thoughts?

roXefeller - 30-5-2018 at 02:29

It would make sense seeing the chlorine as a leaving group. But does neoprene typically exhibit a reactivity to alkali salts? Does that chlorine remain during crosslinking? I tried to briefly answer these myself, but I couldn't find anything obvious.

DubaiAmateurRocketry - 30-5-2018 at 03:07

Quote: Originally posted by roXefeller

It would make sense seeing the chlorine as a leaving group. But does neoprene typically exhibit a reactivity to alkali salts? Does that chlorine remain during crosslinking? I tried to briefly answer these myself, but I couldn't find anything obvious.

Thank you for your input. Hmmm, what do you mean by crosslinking? like after curing? Why would the chlorine not remain? thank you !

Bert - 30-5-2018 at 03:46

Crosslinking = vulcanization, adding other monomers is copolymerization.

Sulfur and heat is the classic crosslinking technology, developed by Goodyear and others back in the 1800s.

Crosslinking with thiocarbamide is a bit more modern, peroxides may be used as well. Ethylene thioureas are effective for crosslinking chloroprene rubber.

You are interested in this for a composite rocket binder/fuel? With lighter elements than Sulfur for crosslinking, perhaps increasing isp? There is also UV radiation based crosslinking, tough to do if you've doped the fuel grain with Carbon black to prevent IR penetrating the fuel grain and accelerating the burn...

[Edited on 5-30-2018 by Bert]

roXefeller - 30-5-2018 at 10:39

I'm not able to get smart about the specifics of neoprene at the moment, but my question was this: what is the process used to vulcanize or crosslink the base polymer (not the monomer). Other polymer systems use a reactive element of the base polymer to initiate the crosslinking, such as double bonds. After that is done the base polymer is less reactive and effectively a massive molecule(s). I suppose the author may be considering sourcing the uncured polymer but will curing still require the chlorine or does it use the double bond?

[Edited on 30-5-2018 by roXefeller]

DubaiAmateurRocketry - 30-5-2018 at 13:28

Quote: Originally posted by Bert

Crosslinking = vulcanization, adding other monomers is copolymerization.

Sulfur and heat is the classic crosslinking technology, developed by Goodyear and others back in the 1800s.

Crosslinking with thiocarbamide is a bit more modern, peroxides may be used as well. Ethylene thioureas are effective for crosslinking chloroprene rubber.

You are interested in this for a composite rocket binder/fuel? With lighter elements than Sulfur for crosslinking, perhaps increasing isp? There is also UV radiation based crosslinking, tough to do if you've doped the fuel grain with Carbon black to prevent IR penetrating the fuel grain and accelerating the burn...

[Edited on 5-30-2018 by Bert]

we can hydroxylterminate the polychloroprene to form HTPCP, now if we add azide groups, it'd be HTPAP. Then it could be cured with isocyanates.

However, straight up polyazidoprene does not need crosslink to cure. cyanide groups can cure it, for example a small amount of polynitrile will cure with the azide groups. the CN N3 forms a tetrazole ring.

[Edited on 30-5-2018 by DubaiAmateurRocketry]

DubaiAmateurRocketry - 31-5-2018 at 16:10

so, any other input if this reaction might work ?

UC235 - 31-5-2018 at 18:59

It will not work. Vinylic halides are unreactive in SN1/SN2 type reactions which is what is being proposed here.

DubaiAmateurRocketry - 31-5-2018 at 22:33

Quote: Originally posted by UC235

It will not work. Vinylic halides are unreactive in SN1/SN2 type reactions which is what is being proposed here.

How come PVC works? Thanks!

UC235 - 1-6-2018 at 02:43

Quote: Originally posted by DubaiAmateurRocketry

Quote: Originally posted by UC235

It will not work. Vinylic halides are unreactive in SN1/SN2 type reactions which is what is being proposed here.

How come PVC works? Thanks!

Despite the name, the chlorine atoms on PVC are not vinylic halides, but alkyl halides, which are quite reactive.